Method and system for color correction for a display terminal

ABSTRACT

A method and system relating to color correction for the display terminal of a display device, such method includes a master control unit generating color adjusting ratios, a display driver using the color adjusting ratios to perform color calibration, and a display panel displaying the resulting colors. Specifically, the master control unit generates adjusting ratios for the RGB color data and the display driver separately adjusts each color according to the percentage of R, G, and B in the ratio to generate a resulting pixel voltage. The system consists of a master control unit, a display driver, and a display panel. The master control unit contains an initialization block, having the following special characteristics: a master control unit with a color adjusting module that receives the color adjusting ratio sent from a color setting block, adjusts color data according to the adjusting ratio, generates the resulting pixel voltage, and displays the colors via a display panel. This invention is easy to operate, inexpensive to produce, and highly practicable.

CROSS REFERENCE

This application claims priority from a Chinese patent applicationentitled “A Method and System for Color Correction for a DisplayTerminal” filed on Dec. 21, 2005, having a Chinese Application No.200510022409.4. This Chinese application is incorporated here byreference.

FIELD OF INVENTION

This invention relates to display devices, and, in particular, to acolor correction method and system for a display terminals.

BACKGROUND OF INVENTION

Currently, color planar display technologies such as LCD, OLED, etc. alltreat color pictures as if they are a pixel array made up of limitedpixels. The display panel of LCD and OLED is a pixel array made up ofpixels which are independent of one another. At the same time, eachpixel consists of three adjacent, relatively independent red, green, andblue pixels. When the three primary colors of red, green, and bluediffer in value, the pixels will display different colors.

The existing display terminal is comprised of three major components, amaster control unit, a display driver, and a display panel. Uponpowering up, the master control unit completes the initialization of alldriver circuits; then the master control unit forwards all display datathat it has received to the display driver, which processes the displaydata, outputs the corresponding voltage, and lights up the correspondingpixels in the display panel. While processing the display data, e.g.,performing gamma adjustment, for many display panels, the relationshipbetween the driving voltage/electric current coming from the displaydriver and the grayscale of display on the display panel is nonlinear.Through gamma adjustment, the linear display of RGB data is converted toa nonlinear display of RGB data on the display panel so that the displaypanel can correctly display the grades of the linear display data.

Generally speaking, each special display panel has only onecorresponding gamma correction value which is provided by themanufacturer. Once the display panel and the display driver areassembled into a display module, the gamma correction value in thedisplay driver will not change.

When manufacturing display panels, the display quality of differentbatches or different display panels in the same batch may differ due tothe different production techniques. When these display panels are madeinto different display terminals, the display results of these displayterminals may be completely different even though the identical displaydata source is used. Some display terminals look more reddish, someappear more bluish, and so on. To solve this problem, the currenttechnology can only resort to raising the manufacturing standard of thedisplay terminals as much as possible while minimizing the variation inproduction technique, which, to a great extent, increases the productcost of the display terminals.

Therefore, it is desirable to have an easy-to-operate, low-cost colorcorrection system and methods to solve the problem of displayinconsistency.

SUMMARY OF INVENTION

This purpose of this invention is to provide an easy-to-operate,low-cost color correction method and system for display terminals inorder to solve the problem of display inconsistency on the displayterminals when using the prior art technologies.

This invention utilizes a color correction method and system wherein themaster control unit generates a color adjusting ratio. The displaydriver according to the said color adjusting ratio performs coloradjustment, and the display panel displays the resulting color.

This color correction method and system for the display terminal maycomprised of the following steps:

A. The master control unit generates an adjusting ratio for the RGBcolor data and forwards it to the display driver;

B. The display driver, according to the R, G, and B content in theadjusting ratio, performs separate adjustments and generates theresponsive pixel voltage; and

C. The display panel displays the resulting color.

Said step A may comprised of the following steps:

A1. The master control unit receives the YCbCr color correction value;

A2. The master control unit, according to the adjusting ratio,calculates the R, G, and B in the corresponding RGB color data andgenerates an adjusting ratio for each of them; and

A3. The master control unit sends the adjusting ratio to the displaydriver.

In said step A1, the YCbCr color correction value can be forwarded tothe master control unit via a respective external input device.

In said step B, the display driver also performs gamma correction on theR, G, and B components and may comprised of the following steps:

B1. The display driver stores in memory the R, G, and B components fromthe adjusting ratio value that it has received;

B2. The display driver, at the minimum, adjusts the R, G, and Bcomponents respectively, according to the adjusting ratio that is storedin the memory; and

B3. Generates the respective pixel voltages.

Said step B2may comprised of the following steps:

B21. The display driver receives the R. G, and B components in thesecond adjusting ratio sent by the master control unit; and

B22. The display driver combines the second adjusting ratio and theadjusting ratio that is stored in the memory, and adjusts the R, G, andB components independently according to the combined ratio.

This color correction system for the display terminal may comprised of amaster control unit, a display driver, and a display panel. The mastercontrol unit may comprised of an initialization block which initializesthe system. The master control unit then forwards data information tothe display driver.

DESCRIPTION OF THE DRAWING

The foregoing and other objects, aspects and advantages of the inventionwill be better understood from the following detailed description of thepreferred embodiments of this invention when taken in conjunction withthe accompanying drawings in which:

FIG. 1 is a block diagram for the overall structure of embodiment 1 ofthis invention;

FIG. 2 is a flowchart illustrating the basic control flow for embodiment1 of this invention;

FIG. 3 is a diagram illustrating the structure for embodiment 2 of thisinvention;

FIG. 4 is a block diagram illustrating a detailed control flow forembodiment 2 of this invention;

FIG. 5 is a diagram illustrating the overall structure of embodiment 3of this invention;

FIG. 6 is a flowchart illustrating the detailed control flow forembodiment 3 of this invention;

FIG. 7 is a block diagram illustrating the overall structure ofembodiment 4 of this invention;

FIG. 8 is a flowchart illustrating the detailed control of embodiment 4of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The presently preferred embodiment of this invention utilizes a colorcorrection method and system wherein the master control unit generates acolor adjusting ratio. The display driver according to the said coloradjusting ratio performs color adjustment, and the display paneldisplays the resulting color.

This color correction method and system for the display terminal maycomprise of the following steps:

-   -   B. The master control unit generates an adjusting ratio for the        RGB color data and forwards it to the display driver;    -   C. The display driver, according to the R, G, and B content in        the adjusting ratio, performs separate adjustments and generates        the responsive pixel voltage; and    -   D. The display panel displays the resulting color.

Said step A is comprised of the following steps:

A1. The master control unit receives the YCbCr color correction value;

A2. The master control unit, according to the adjusting ratio,calculates the R, G, and B in the corresponding RGB color data andgenerates an adjusting ratio for each of them; and

A3. The master control unit sends the adjusting ratio to the displaydriver.

In said step A1, the YCbCr color correction value can be forwarded tothe master control unit via a respective external input device.

In said step B, the display driver also performs gamma correction on theR, G, and B components.

Said step B is comprised of the following steps:

B1. The display driver stores in memory the R, G, and B components fromthe adjusting ratio value that it has received;

B2. The display driver, at the minimum, adjusts the R, G, and Bcomponents respectively, according to the adjusting ratio that is storedin the memory; and

B3. Generates the respective pixel voltages.

Said step B2 is comprised of the following steps:

B21. The display driver receives the R. G, and B components in thesecond adjusting ratio sent by the master control unit; and

B22. The display driver combines the second adjusting ratio and theadjusting ratio that is stored in the memory, and adjusts the R, G, andB components independently according to the combined ratio.

This color correction system for the display terminal is comprised of amaster control unit, a display driver, and a display panel. The mastercontrol unit is comprised of an initialization block which initializesthe system. The master control unit forwards data information to thedisplay driver. The master control unit further may comprise of a colorsetting block which derives the color adjusting ratio value.

Said display driver may comprise of a color adjusting module whichreceives the color adjusting ratio sent by the color setting block,performs the color correction according to said adjusting ratio,generates respective pixel voltages, and displays the color via thedisplay panel.

The color adjusting module may comprise of an adjustment module for Rcomponents, an adjustment module for G components, and an adjustmentmodule for B components. The color setting block derives an adjustingratio for R, G, and B components respectively and forwards themseparately to the adjustment module for R components, the adjustmentmodule for G components, and the adjustment module for B components.

The display driver further includes memory which stores adjusting ratiosfor R, G, and B components. Said color adjustment module performsrespective adjustments according to the adjusting ratios stored in thememory.

The color setting block may comprise of an interface sub module foradjusting data and a calculating sub module, wherein said interface submodule for adjusting data receives YCbCr color correction values andforwards them to the calculating sub module. The said calculating submodule, according to the existing RGB color data and the YCbCr coloradjusting ratios, performs RGB color data calculation to calculate theR, G, and B components in the adjusting ratio and forwards the resultsof the calculation to the color adjustment module.

The color setting block further may comprise of a corrected data inputmodule which forwards the YCbCr color correction value to the interfacesub module for adjusting data.

The display driver may further comprise of a gamma adjustment modulewhich performs gamma correction for the color data.

The benefits of this invention are that in this invention the mastercontrol unit generates the color adjusting ratio, the display driverperforms color correction according to the said color adjusting ratio;and the display panel displays the respective colors. It is theequivalent of using the master control unit to make the display driverpre-adjust the colors. This pre-adjustment can simply compensate for thevariation in display caused by the differences in the display panels.For instance, in this invention, the master control unit generates anadjusting ratio for the RGB color data and forwards it to the displaydriver. The display driver, according to the R, G, and B components(i.e., the red, green, and blue components), performs adjustments forthe red, green, and blue components respectively, generates the pixelvoltages for these three colors, and displays the respective colors onthe display panel. The colors displayed are corrected colors. Incomparison with existing technologies, this method is simple and easy toimplement, achieves display consistency in the display terminal, reducesrequirements for the display panel, and keeps the production costrelatively low.

In the embodiments of this invention, setup using the YCbCr coloradjusting ratio makes YCbCr color coding more straightforward, namelysimply specifying the brightness component Y, the bluish color componentCb, and the reddish color component Cr. The ease of operation furtherenhances the practicality of this invention.

In the embodiments of this invention, the display driver stores inmemory the R, G, and B components of the adjusting ratio and, accordingto the adjusting ratio stored in the memory, performs independentadjustments of the R, G, and B components to generate the respectivepixel voltage. In fact, this method can achieve the relative stabilityin color pre-correction as mentioned in this invention. For theproduction of display terminals, such stability can ensure consistencyin product quality (display consistency), thus making this inventionwidely applicable and enhancing its practicality.

At the same time, the displayed RGB data adjustment of this invention isdone by the adjustment module (hardware) of the display driver, greatlyreducing the time that would otherwise be used by the master controlunit for display. For example, for a display module with a pixel arrayof 132×132, the master control unit will have to send 132×132=17424display data to the display driver for each picture that is displayed.If the data correction is done by the master control unit (assuming thatthe master control unit will consume two processing cycles forprocessing a single data), then for the time it takes the master controlunit to adjust each picture, the RGB data equals to 17424×2=34848processing cycles; whereas it takes the master control unit a fractionof the time prior to the display to set up the adjusting ratio in theadjustment module when data is adjusted via the display driver. Storingthe adjusting ratio in non-volatile memory also saves the setup time.

In the embodiments of this invention, the display driver also receivesthe second adjusting ratio for the R, G, and B components forwarded bythe master control unit. For instance, by setting the data for themaster control unit using the respective external input devices or theadjustment data input module in the color setting block, coupled withthe adjusting ratio stored in the memory, this second adjusting ratiocan provide custom setup for the user, making this invention morecustomizable and further enhances the applicability of this invention.

The following sample embodiments provide a further detailed descriptionof this invention:

Embodiment 1

According to FIGS. 1 and 2, this invention includes a master controlunit 1, a display driver 2, and a display panel 3. The master controlunit 1 is comprised of an initialization block 11 and a color settingblock 12, wherein the initialization block 11 initializes the system.The master control unit 1 forwards display data to display driver 2. Thecolor setting block 12 generates a color adjusting ratio and forwards itto the display driver 2.

According to FIG. 1, the display driver 2 is comprised of a coloradjustment module 21, which receives the color adjusting ratio generatedby the color setting block 12, performs color correction according tothe adjusting ratio, generates the respective pixel voltages, anddisplays the respective colors via the display panel 3.

As illustrated in FIG. 2, the basic control flow for this embodiment isas follows:

1) The color setting block 12 in the master control unit 1 generates anadjusting ratio for the RGB color data and forwards it to the coloradjustment module 21 in the display driver 2;

2) The color adjustment module 21, according to the R, G, and Bcomponents in the adjusting ratio, performs separate adjustments,generates the respective red, green, and blue pixel voltages, and passesit on to the display panel 3; and

3) The display panel 3 displays the respective colors.

In this method, the master control unit 1 generates the color adjustingratio. The display driver 2, according to the adjusting ratio, performscolor correction and the display panel 3 displays the respective colors.

Embodiment 2

According to FIGS. 3 and 4, this invention is comprised of a mastercontrol unit 1, a display driver 2, and a display panel 3. The mastercontrol unit 1 is comprised of an initial block 11 and a color settingblock 12. The initial block 11 initializes the system. The mastercontrol unit 1 forwards display data to the display driver 2. The colorsetting block 12 generates a color adjusting ratio and forwards it tothe display driver 2.

Specifically, as illustrated in FIG. 3, the color setting block 12 iscomprised of an interface sub module for adjusting data 121 and acalculating sub module 122, wherein the interface sub module foradjusting data 121 receives the YCbCr color correction value andforwards it to the calculating sub module 122. The interface sub modulefor adjusting data 121 receives the setting data from the respectiveexternal input device 4.

As illustrated in FIG. 3, the calculating sub module 122, according tothe existing RGB color data and the YCbCr color correction value,performs RGB color data conversion to calculate the R, G, and Bcomponents in the adjusting ratio and forwards the results of thecalculation to the color adjustment module 21. The conversion betweenthe RGB color data and the YCbCr color data is performed as follows:

In the YCbCr color space, wherein the “Y” represents brightness, “Cr”represents the red components in the color spectrum of the light source.“Cb” represents the blue components in the color spectrum of the lightsource. When increasing the intensity of brightness of the picture, thevalue of Y is increased while keeping the values of Cb and Cr unchanged.When decreasing color temperature, the values Cb/Cr is decreased and thevalue of Cr is increased to increase the red color component whilekeeping the value of Y unchanged. However, because the display paneldisplays the RGB color space, the YCbCr values must be converted to RGBvalues. According to the BT-160 standard, the conversion between theYCbCr color space and the RGB color space uses the following formulas:Y=(77R+150G+29B)/256 Range: 16_(˜)235Cb=(−44R−87G+131B)/256+128 Range: 16_(˜)240Cr=(131R−110G−21B)/256+128 Range: 16_(˜)240Thus: R=Y+1.371(Cr−128)G=Y−0.698(Cr−128)−0.336(Cb−128)B=Y+1.732(Cb−128)

According to the aforementioned formulas, the calculating sub module 122converts the correction of color temperature/brightness that thecorrected data interface 121 has received to the RGB adjusting ratio,and forwards it to the color adjustment module 21.

As illustrated in FIG. 3, the display driver 2 is comprised of the coloradjustment module 21, wherein the color adjustment module 21 receivesthe color adjusting ratio sent out by the color adjustment module 12,performs color data adjustment according to the adjusting ratio,generates the respective pixel voltages and displays the respectivecolors via the display panel 3. The color adjustment module 21 iscomprised of an R component adjustment module 211, a G componentadjustment module 212, and a B component adjustment module 213. Theadjusting ratios for the R, G, and B components generated by thecalculating sub module 122 are forwarded to the R component adjustmentmodule 211, the G component adjustment module 212, and the B componentadjustment module 213, respectively. As illustrated in FIG. 3, thedisplay driver also is comprised of the respective gamma adjustmentmodules 231, 232, and 23. The gamma adjustment modules 231, 232, and 233perform gamma correction on the R, G, and B color data.

As illustrated in FIG. 4, the specific control flow of this embodimentis as follows:

a) The interface sub module for adjusting data 121 in the master controlunit 1 receives the YCbCr color correction value sent by the inputdevice 4 and forwards it to the calculating sub module 122;

b) The calculating sub module 122, according to the correction that ithas received, calculates the R, G, and B components in the respectiveRGB color data to derive the adjusting ratios for each component;

c) The calculating sub module 122 forwards the adjusting ratios for theR, G, and B components to the respective R component adjustment module211, the G component adjustment module 212, and the B componentadjustment module 213 within the display driver 2;

d) The R component adjustment module 211, the G component adjustmentmodule 212, and the B component adjustment module 213 perform separateadjustments, according to the R, G, and B components in the adjustingratio and also perform respective gamma corrections via the gammaadjustment modules 231, 232, and 233;

e) Generates the respective red, green, and blue pixel voltages andpasses it on to the display panel 3; and

f) Displays the respective colors on the display panel 3.

Embodiment 3

According to FIGS. 5 and 6, this embodiment differs from embodiment 2 inthat the display driver 2 in this embodiment is further comprised of amemory 22. The memory 22 retains the R, G, and B components of theadjusting ratio. The color adjustment module 21, according to theadjusting ratio retained in the memory 22, performs respectiveadjustments.

As illustrated in FIG. 6, the specific control flow for this embodimentis as follows:

I. The interface sub module for adjusting data 121 in the master controlunit 1 receives the YCbCr color correction value sent forwarded by theinput device 4 and passes it on to the calculating sub module 122;

II. The calculating sub module 122, according to the correction valuethat it has received, calculates the R, G, and B components in therespective RGB data and generates the adjusting ratio for eachcomponent;

III. The calculating sub module 122, forwards the adjusting ratios forthe R, G, and B components to non-volatile memory 22 in the displaydriver 2;

IV. The memory 22, stores the received adjusting ratios for the R, G,and B components;

V. The R component adjustment module 211, the G component adjustmentmodule 212, and the B component adjustment module 213, according to theadjusting ratios for the R, G, and B components, perform respectiveadjustments, and conduct gamma correction via the respective gammacorrection module 231, 232, and 233;

VI. The respective red, green, and blue pixel voltage is generated andis passed on to the display panel 3; and

VII. The display panel 3 displays the respective colors.

In this embodiment, the memory 22, functions in such a way that, in theembodiment of this invention, though the input device 4 may not load thecorrection value at the next power-on, the adjusting ratio for the R, G,and B components that are stored in memory 22 still functions. Thisadjustment provides relative stability.

Embodiment 4

According to FIGS. 7 and 8, the main difference between this embodimentand embodiment 3 is that the color setting block 12, as in thisembodiment is further comprised of a correction data input module 120.The correction data input module 120 forwards the YCbCr color correctionvalues to the interface sub module for adjusting data 121.

As illustrated in FIG. 8, the specific control flow of this embodimentis as follows:

The interface sub module for adjusting data 121 receives the YCbCr colorcorrection values and forwards them to the calculating sub module 122;

The calculating sub module 122, according to the received correctionvalues, calculates the R, G, and B components of the respective colordata to generate the initial correction values for each component;

The calculating sub module 122 forwards the initial adjusting ratios ofthe R, G, and B components to the EEPROM 22 on the display driver 2;

The memory 22, stores the initial adjusting ratios of the R, G, and Bcomponents that were received;

The interface sub module for adjusting data 121 receives the YCbCr colorcorrection values that are forwarded by the correction data input module120 and passes them on to the calculating sub module 122;

The calculating sub module 122, according to the received correctionvalues, calculates the respective R, G, and B components of the RGBcolor data to generate the second adjusting ratios for each component;

The calculating sub module 122 forwards the second adjusting ratios tothe R component adjustment module 211, the G component adjustment module212, and the B component adjustment module 213;

The R component adjustment module 211, the G component adjustment module212, and the B component adjustment module 213 combine separately the R,C, and B components in the second adjusting ratios and the initialadjusting ratios that are stored in the memory 22. They then performseparate adjustments for each of the combined values and make therespective gamma corrections;

The respective the red, green, and blue pixel voltages that aregenerated are passed on to the display panel 3; and

The respective colors are displayed on the display panel 3.

In this embodiment, the interface sub module for adjusting data 121 ofstep 1 can receive data via an external input device 4 and can alsoreceive data from the correction data input module 120. Steps 1 through4 represent the relative fixed setting for color adjustment, namely, themanufacturers in using this invention to provide uniformity (in theproducts); whereas the correction values of step 5 represent personalsetting of the specific users (customers). More applications can be madeusing this invention, which can be implemented by technicians in thisfield without making any creative effort. No further elaboration iswarranted here.

While the present invention has been described with reference to certainpreferred embodiments, it is to be understood that the present inventionis not limited to such specific embodiments. Rather, it is theinventor's contention that the invention be understood and construed inits broadest meaning as reflected by the following claims. Thus, theseclaims are to be understood as incorporating not only the preferredembodiments described herein but also all those other and furtheralterations and modifications as would be apparent to those of ordinaryskilled in the art.

1. A method for color correction for a display terminal, having a mastercontrol unit generating a color adjusting ratio, a display driverperforming color adjustment according to said color adjusting ratio, anda display panel displaying the adjusted colors, comprising the steps of:generating color adjusting ratios by said master control unit for RGBcolor data and forwarding the color adjusting ratios to the displaydriver; adjusting by said display driver, in accordance with the coloradjusting ratios, separate adjustments to RGB components and generatingrespective digital pixel voltages; and displaying on the display panelin accordance with generated digital pixel voltages.
 2. The method ofclaim 1, wherein the generating step further includes the followingsteps: the master control unit receiving an YCbCr color correctionvalue; the master control unit, according to the correction value,calculating the RGB percentage contained in the RBG color data andgenerating color adjusting ratios for each RGB component; and the mastercontrol unit forwarding the generated color adjusting ratios to thedisplay driver.
 3. The method of claim 2 wherein the YCbCr colorcorrection value is sent to the master control unit via a correspondingexternal input device.
 4. The method of claim 1 wherein the displaydriver also performing gamma adjustment to the RGB components.
 5. Themethod of claim 2, further including the following steps: the displaydriver storing the received RGB color adjusting ratios in memory; thedisplay driver, at least according to the color adjusting ratios storedin memory, performing separate adjustments for the RGB components; andgenerating the respective pixel voltages.
 6. The method of claim 5,further comprising the steps of: the display driver receiving one ormore second adjusting ratios for the RGB components from the mastercontrol unit; and the display driver separately adding the secondadjusting ratios and the color adjusting ratios stored in the memory,and adjusting the RGB components accordingly.
 7. A color correctionsystem for display terminals, comprising: a master control unit havingan initialization block for performing system initialization and a colorsetting block for generating color adjusting ratios; a display driverhaving a color adjustment module for receiving the color adjustingratios from the color setting block, and adjusting color data accordingto the color adjusting ratios, and generating the respective pixelvoltages; and a display panel for displaying adjusted color data inaccordance with the respective pixel voltages.
 8. The system of claim 7,wherein: the color adjustment module having for RGB components a Radjusting sub module, a G adjusting sub module, and a B adjusting submodule; and the color setting block generating adjusting ratios valuefor the RGB components and forwarding them separately to the R adjustingsub module, the G adjusting sub module, and the B adjusting module. 9.The system of claim 8 wherein the display driver having a memory unit,wherein the memory unit contains the adjusting ratios for the RGBcomponents, and the color adjustment module performing the correspondingadjustments according to the adjusting ratios in the memory unit. 10.The system of claim 7 wherein the said color setting block having acorrection data input module and a calculating sub module, wherein; thecorrection data input module receives one or more YCbCr color correctionvalues and forwards the YCbCr color correction values to the calculatingsub module; and the calculating sub module, according to RGB color dataand the YCbCr color correction values, converts the color data, computesthe adjusting ratios for the RGB components, and sends the convertedcolor data and the adjusting ratios to the color adjusting module. 11.The system of claim 8 wherein the said color setting block having acorrection data input module and a calculating sub module, wherein; thecorrection data input module receives one or more YCbCr color correctionvalues and forwards the YCbCr color correction values to the calculatingsub module; the calculating sub module, according to RGB color data andthe YCbCr color correction values, converts the color data, computes theadjusting ratios for the RGB components, and sends the converted colordata and the adjusting ratios to the color adjusting module.
 12. Thesystem of claim 7 wherein the display driver further comprising of aGamma adjustment module for performing Gamma adjustments on the colordata.
 13. The system of claim 8 wherein the display driver furthercomprising of a Gamma adjustment module for performing Gamma adjustmentson the color data.
 14. The system of claim 10 wherein the display driverfurther comprising of a Gamma adjustment module for performing Gammaadjustments on the color data.
 15. The system of claim 11 wherein thedisplay driver further comprising of a Gamma adjustment module forperforming Gamma adjustments on the color data.